KR100688624B1 - Nozzle tip of bunner - Google Patents

Abstract

The present invention provides an inner cell having a first passage through which a mixture of fine fuel and air discharged into a furnace from a fuel distribution pipe and a secondary air introduced from an air conduit between the inner cells and into the furnace. An outer cell installed to be isolated outside the inner cell so as to have a second passage for the at least one central baffle installed to partition the first passage inside the inner cell, and at least one installed to partition the second passage In the nozzle tip of the fine fuel burner configured as an outer baffle;

The nozzle tip is produced by dividing the nozzle tip into the front nozzle tip and the rear nozzle tip, wherein the front nozzle tip is produced by casting, and the front and rear lengths are 1/3 of the total length of the nozzle tip. The nozzle tip of the burner.

Thermal power plant, burner, nozzle tip

Description

Nozzle tip of fine fuel burner {Nozzle tip of bunner}             

1 is a configuration diagram of a boiler for fine fuel combustion

2 is a view showing a tangential injection method

3 is an installation state diagram of a fuel-air injection device (perspective view)

4 is a state diagram (fuel cross section) of the fuel-air injection device

5 is a thermal deformation state of the nozzle tip

6 is a schematic view (perspective view) of a detachable nozzle tip

7 is a schematic view (section view) of the detachable nozzle tip

8 is a perspective view of a detachable nozzle tip according to the present invention;

9 is a perspective view of the combination of the detachable nozzle tip according to the present invention

10 is a state in which the cooling pipe is installed in the detachable nozzle tip according to the invention

11 is a state in which the mesh is installed on the cooling pipe

12 is a state in which the refractory is applied on the mesh

13 is a cross-sectional view taken along the line II of FIG.

14 is a cross-sectional view taken along the line II-II of FIG. 12.

15 is a cross-sectional view taken along the line III-III of FIG.

[Description of Symbols for Main Parts of Drawing]

2c-1: inner cell 2c-2: outer cell

10: nozzle tip 11: front nozzle tip

12: rear nozzle tip l: front and rear length of nozzle tip

13: cooling pipe 14: refractory

The present invention relates to a nozzle tip for a differential fuel burner for a thermal power plant, and more particularly, while the nozzle tip is divided into front and rear parts, in particular, the nozzle tip of the first half is manufactured by casting, but for ease of casting operation. Minimize load on vertical rotation of nozzle tip by making 1/3 of nozzle tip length and making the thickness of 6 ~ 10mm, the minimum thickness that can be applied in casting in casting the first half of nozzle tip And a nozzle tip of a fine fuel burner characterized in that the first half of the nozzle tip is made of heat-resistant cast steel to prevent thermal deformation.

As is well known, coal-fired power plants supply finely powdered, pulverized coal, in pulverizers through conduits, and supply this coal to the air at a constant rate in a damper. The mixture is introduced into the furnace 1 of the boiler B and combusted to vaporize water in the water pipe, and the turbine is rotated by the steamed steam to generate electricity (see FIG. 1).

At this time, a tangential injection method known as one of the general methods for burning fine fuel such as carbon in the steam generator 1 is used. In this tangential injection method, the fuel-air flow emitted from the fuel-air injection device 2 located at each corner of the quadrangular furnace 1 as shown in FIG. 2 is tangentially directed toward the virtual circle C at the center of the furnace. It refers to a method of forming a flame in the furnace (1) while spraying.

The fuel-air injection device (2) surrounds a fuel distribution pipe (2a) for sending pulverized coal mixed with air to the furnace (1), and a fuel distribution pipe for sending air to the furnace as shown in FIGS. 3 and 4. It consists of several nozzle tips 2c arranged in the up-and-down direction which are installed up and down rotationally at the outlet end of the air conduit 2b and the fuel distribution line.

A typical configuration of the nozzle tip 2c includes an inner cell 2c-1 and an outer cell 2c-2 disposed axially in a relation to each other as shown in FIG. 4, from the fuel distribution pipe to the furnace. The first flow path 2c-3 in the inner cell through which the mixture of fine fuel and air discharged into the inside flows, and the second flow path in the annular space between the inner cell and the outer cell through the secondary air discharged from the air conduit into the furnace ( 2c-4). In addition, one or more baffles 2c-5 are disposed inside the inner cell 2c-1 to exert an additional directional force on the coal-air stream discharged through the inner cell, and in particular, a nozzle for controlling steam temperature. It is arranged parallel to the longitudinal axis s to evenly distribute the coal-air stream when inclined from the horizontal.

An important problem in using the nozzle tip (2c) is the problem of heat deformation due to the internal temperature and radiant heat of the boiler up to about 1000 ℃ is the most serious. In particular, in the case where the first half and the second half of the nozzle tip are integrated, the tip of the first half undergoes thermal expansion while the nozzle tip of the second half acts to restrain the thermal expansion, thereby causing extreme thermal stress on the nozzle tip of the first half. The cracks and deformations of the welded portion are weakened. Fig. 5 shows the deformed state of the nozzle tip 2c, which is actually more severe than that shown in the drawings.

When the nozzle tip 2c is configured to be separated into the first half 2c 'and the second half 2c ", the front half of the nozzle tip is connected to the upper and lower pads p as shown in FIG. Even if it occurs at the nozzle tip (2c ') of the front and rear nozzle tip (2c', 2c ") except the pad is separated, the thermal expansion and contraction of the front nozzle tip is relatively smooth, so that the thermal stress can be drastically reduced compared to the one-piece. As a result, the thermal deformation can be significantly reduced. In addition, when the first half nozzle tip 2c 'is deformed, the rear half nozzle tip 2c "may be replaced with only the first half nozzle tip, thus having a considerable economic advantage over the integrated nozzle tip.

However, the nozzle tip 2c 'of the first half has a baffle 2c-5 and 2c-6 between the center of the inner cell 2c-1 and the inner cell 2c-1 and the outer cell 2c-2, respectively. Due to the welded by, the degree of heat deformation at this welded part is serious and its life is not long. Therefore, the replacement period of the front part nozzle tip 2c 'has a short problem.

In order to replace the nozzle tip, the thermal power plant must be shut down. Therefore, the replacement period of the nozzle tip is usually set to two years to reduce the loss due to such downtime. However, the conventional nozzle tip is a thermal deformation occurs after a year or so after installation, but the use of a further one year in a deformed state to reduce the loss due to the downtime is causing the efficiency of the boiler.

Moreover, the conventional nozzle tip uses STS310S, which is a kind of stainless steel, but this STS310S has no problem of heat resistance up to about 900 ℃, but it deforms after 900 ℃. It will not withstand temperature and radiant heat and will deform.

Accordingly, the present invention has been made to solve the conventional problems as described above, the object of the present invention is to cast the nozzle tip of the first half using a heat-resistant alloy heat-resistant and heat-resistant, the heat resistance and wear resistance of the first half nozzle tip Improve the; In order to ensure the ease of casting operation, the length of the front nozzle tip is reduced to about 1/3 of the total length of the nozzle tip, and the thickness of the front nozzle tip is 6-10mm, which is the minimum thickness that can be applied in casting. It is to provide a nozzle tip of a fine fuel burner having a characteristic.

The object of the present invention described above,

An inner cell having a first flow path through which a mixture of fine fuel and air discharged into the furnace from the fuel distribution pipe in the center and a second air for discharging secondary air introduced from the air conduit between the inner cell into the furnace An outer cell installed to be isolated outside the inner cell so as to have a flow path, at least one central baffle to partition the first flow path inside the inner cell, and at least one outer baffle to partition the second flow path In the nozzle tip for the fine fuel burner configured;

The nozzle tip is divided into a front nozzle tip and a rear nozzle tip, but the front nozzle tip is produced by casting, characterized in that the front and rear length including 1/3 so that the front and rear length of the entire nozzle tip.

At this time, the thickness of the front nozzle tip is characterized in that 6 ~ 10mm.

In addition, the front nozzle tip is carbon 0.2 ~ 0.5 (wt%), silicon 2.0 (wt%), manganese 2.0 (wt%), phosphorus 0.04 (wt%), sulfur 0.04 (wt%), nickel 11 to 14 (wt%) and chromium 24 to 28 (wt%), characterized in that the casting is made of a heat-resistant alloy steel.

In addition, the front nozzle tip is 0.35 to 0.70 (wt%), silicon 2.5 (wt%), manganese 2.0 (wt%), phosphorus 0.04 (wt%), sulfur 0.04 (wt%), nickel It may be cast from a heat-resistant alloy steel composed of 33 to 37 (wt%) and chromium 15 to 19 (wt%).

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

8 is a perspective view of the detachable nozzle tip according to the present invention, FIG. 9 is a cross-sectional view of the detachable nozzle tip according to the present invention, FIG. 10 is a state diagram in which a cooling pipe is installed on the detachable nozzle tip according to the present invention, and FIG. 12 is a state diagram in which a mesh is installed on a cooling pipe, FIG. 12 is a state diagram in which refractory is applied on a mesh, FIG. 13 is a cross-sectional view taken along line II of FIG. 12, FIG. 14 is a cross-sectional view taken along line II-II of FIG. 12, and FIG. A sectional view taken along the line III-III of FIG. 12 is shown.

The present invention relates to an inner cell (2c-1) having a first flow passage (2c-3) through which a mixture of fine fuel and air discharged into a furnace from a fuel distribution pipe in the center thereof, and from an air conduit between the inner cells. An outer cell 2c-2, which is installed to be isolated to the outside of the inner cell so as to have a second flow path 2c-4 for releasing the introduced secondary air into the furnace, and a first flow path inside the inner cell. From the nozzle tip for fine fuel burner consisting of at least one central baffle (2c-5) and one or more outer baffles (2c-6) are installed to partition the second flow path,

The nozzle tip 10 is divided into a front nozzle tip 11 and a rear nozzle tip 12, but the front nozzle tip 11 is manufactured by casting, while the front and rear lengths of the entire length of the nozzle tip front and rear (ℓ) It is the first feature that it is l / 3. (Previously it was about l / 2. In FIG. 9, the dotted line is the boundary between the existing front nozzle tip and the rear nozzle tip.)

The reason for limiting the length of the front nozzle tip 11 is because of the limitation of casting. In order to increase the precision of casting, the length and thickness should be appropriately limited. For that reason, the length of the front nozzle tip is limited, and the limit of the titration is about l / 3 of the total length of the nozzle tip. In addition, since the most active portion of the thermal deformation in the nozzle tip 10 is the point of the front L / 3 point, in this sense it can be seen that the limit of the length of L / 3 is important.

In this case, since the l is typically about 440 mm, the l / 3 is about 147 mm. Therefore, the length range of the front nozzle tip 11 should not exceed about 150 mm in view of the error.

If the total length of the nozzle tip (l) far exceeds 440mm, the length of the front nozzle tip 11 should not be set to l / 3. For example, assuming that l is 600 mm, its l / 3 will be 200 mm, so as described above, it exceeds the 150 mm limit for good casting. Therefore, if l is well over 440mm, the formula of l / 3 cannot be applied.

On the other hand, the thickness of the front nozzle tip 11 should be within the range of 6 ~ 10mm, the reason is also for good casting as described above. This is shown in Table 1 below.

Table 1 (Unit: mm)

 Kinds  sign Thickness of casting length <100 100- 200 200 ~ 400 400 ~ 800 800 ~ 1250 1250 ~ 2000 2000 ~ 3200  Cast iron GC10,15 3 3 4 5 6 8 10 GC20,25 4 4 5 6 8 10 12 GC30,35 5 5 6 8 10 12 16 Nodular cast iron GCD40,45,50 5 5 6 8 10 12 16 GCD60,70 6 6 8 10 12 16 20 Carbon Steel Cast Steel 0 5 5 6 8 12 16 20 Low Manganese River 6 6 8 12 16 20 25 Etc 8 8 8 12 16 20 25 High Manganese River 8 8 10 12 16 20 25 Stainless Cast Steel (Chrome) 10 10 12 16 20 25 -             (Chrome nickel system) 8 8 10 12 16 20 - Heat Resistant Alloy (Chrome) 10 10 12 16 20 25 -         (Chrome nickel system) 6 8 10 12 16 20 - Aluminum alloy casting (sand mold) 3 4 5 6 8 - -                 (mold) 2.5 3 4 5 - - -

(In Table 1, 100 ~ 3200mm is the length of casting, and below 2.5 ~ 25 is the thickness of titration for casting length.)

As shown in Table 1, the material of the front nozzle tip of the present invention will be described later, but considering the length (about 440 mm) of the front nozzle tip 11 because it is chromium nickel-based and heat-resistant alloy steel, the thickness range is 6 to 10 mm. Should be. If it is less than this thickness range, it is impossible to inject molten metal and casting of the proper nozzle tip shape will be difficult, and the defective product will be mass-produced. This is undesirable because load is expected.

On the other hand, the material of the front nozzle tip 11 is made of heat-resistant cast steel resistant to heat and corrosion. As shown in (Table 2) below, there are 10 types of heat-resistant cast steels, that is, stainless steels, each having a different chemical composition ratio.

Table 2

sign Chemical composition (% by weight) C Si Mn P S Ni Cr SCH1 0.20-0.40 1.30-1.50 1.00 0.040 0.040 1.00 12.00-15.00 SCH2 0.40 or less 2.00 1.00 0.040 0.040 1.00 25.00-28.00 SCH3 0.40 or less 2.00 1.00 0.040 0.040 1.00 12.00-15.00 SCH11 0.40 or less 2.00 1.00 0.040 0.040 4.00-6.00 24.00-28.00 SCH12 0.20-0.40 2.00 2.00 0.040 0.040 8.00-12.00 18.00-23.00 SCH13 0.20-0.50 2.00 2.00 0.040 0.040 11.00-14.00 24.00-28.00 SCH15 0.35-0.70 2.50 2.00 0.040 0.040 33.00-37.00 15.00-19.00 SCH16 0.20-0.35 2.50 2.00 0.040 0.040 33.00-37.00 13.00-17.00 SCH17 0.20-0.35 2.00 2.00 0.040 0.040 8.00-11.00 26.00-30.00 SCH18 0.20-0.50 2.00 2.00 0.040 0.040 14.00-18.00 26.00-30.00

The front nozzle tip 11 in the present invention intends to select any one of SCH13 and SCH15 in Table 2, and the selection criteria focus on the content of nickel (Ni). In other words, the higher the nickel content, the stronger the heat resistance of the heat up to about 1000 ° C. (boiler internal temperature + radiant heat), but the disadvantage is that the price is expensive as a counterpart.

In addition, chromium (Cr) is an indispensable element in order to improve high temperature corrosion resistance, and combines with oxygen in an atmosphere to form a Cr ₂ O ₃ film to exhibit good high temperature corrosion resistance. If the content of chromium is less than 15% by weight at temperatures exceeding 1000 ° C, the corrosion resistance may not be sufficiently exhibited. If it exceeds 28% by weight, the α-Cr layer, which is harmful to high temperature corrosion resistance, may precipitate. . Therefore, the content ratio of chromium should be made within the range of 15 to 28% by weight (%).

In addition, the carbon (C) added to the heat-resistant alloy material of the present invention is preferably less from the viewpoint of corrosion resistance, but has the effect of improving the mechanical strength and castability. Therefore, the addition ratio of carbon should not exceed 0.70 weight (%) at maximum.

Silicon (Si) is an effective element for lowering the high temperature strength or improving the castability and the oxidation resistance. 2.00 weight (%) which is effective in improving castability was limited to the minimum content, and when the corrosion resistance rather than strength is needed as the material, the content of silicon is increased to 2.50 weight (%) in the range where strength reduction is not a problem. ) To the highest content. Although the amount of normal silicone addition is about 0.3-1.0 weight%, the preferable range for improving corrosion resistance is 2.00-2.50 weight%.

Manganese (Mn) decreases oxidation resistance and high temperature strength, so that a large amount of addition is not desirable, but it is effective for casting as a casting and also as a deoxidizer and a desulfurizer. Therefore, it is preferable to add manganese below 2.00 weight% in the range which does not significantly reduce oxidation resistance and high temperature strength.

Phosphorus (P) and sulfur (S) are unavoidable impurities contained in steel, and when included excessively, it causes grain embrittlement. For this reason, the upper limit was made into 0.040 weight (%). The lower the content of phosphorus and sulfur, the more preferable.

Meanwhile, as shown in FIGS. 10 to 15, the surfaces of the front nozzle tip 11 and the rear nozzle tip 12 may further include cooling means to enhance heat resistance. This cooling means is a cooling pipe 13 provided on the surface of the nozzle tip 10.

The inlet 13a and the outlet 13b of the cooling pipe 13 are located between the outer cell 2c-2 and the inner cell 2c-1, that is, the second flow path 2c-4, and the remaining portion Is located on the outer surface of the outer cell (2c-2). This is for cooling the front nozzle tip 11 by using the air injected through the second flow path 2c-4, and the air introduced through the inlet 13a of the cooling pipe 13 is the outer cell 2c. Heat is absorbed while passing through the cooling pipes 13 arranged in a zigzag pattern on the outer surface of the -2), and the heat-absorbed air passes through the outlet 13b of the cooling pipes 13 again to the second flow path 2c-4. Has a structure that is sprayed.

In addition, the refractory 14 is coated to protect the cooling pipe 13 and the front nozzle tip 11 from high heat. In order to coat the refractory 14, the outer surface of the outer cell 2c-2 is covered. A plurality of anchors 15 are fixed and the mesh net 16 is joined and then the refractory 14 is poured over and coated. The anchor 15 or the mesh net 16 is to prevent the refractory from falling or cracking. At this time, the shape and size of the anchor 15 may be used in the form of a variety of anchors "V, Y, BOLT" depending on the size of the nozzle tip 10 and the location of the work site.

Therefore, the front nozzle tip 11, which receives the most radiant heat by the flame sprayed from the first flow path 2c-3 of the nozzle tip 10, is protected by the refractory 14 and the cooling pipe 13, thereby providing a superior performance. It will have heat resistance and durability.

The refractory 14 is to minimize the heat deformation of the welded portion of the nozzle tip 10 due to the radiant heat generated during the combustion of the boiler (B), the material of the refractory 14 is excellent in heat resistance, workability It is preferable that a refractory material having a material such as easy alumina cement, magnesia, zirconia or the like is applied.

In addition, the coal powder by hard facing the projection jaw (11a) and the central baffle (2c-5) formed on both sides and the upper and lower sides of the inner cell (2c-1) of the front nozzle tip (11) The strong injection of air and air prevented the inner cell 2c-1 of the front nozzle tip 11 from being eroded and damaged by abrasion, thereby improving durability and wear resistance of the nozzle tip 11. At this time, the hard facing is formed to a thickness of about 3 ~ 6mm and the material was a stellite. It has excellent abrasion resistance, low coefficient of friction, no damage to other metals, excellent corrosion resistance, high hardness at high temperature and very good corrosion resistance. Excellent effect on parts requiring corrosion.

Unexplained reference numeral 11b is provided on both sides of the front nozzle tip 11, and is a fixed shaft located between the inner cell (2c-1) and the outer cell (2c-2), 12a is provided on both sides in front of the rear nozzle tip It is a hanger plate which has the slot 12b of the upper opening type so that the fixed shaft 11b may be fitted from the top.

As described above, the present invention contributes to life extension by further improving heat resistance, corrosion resistance, and abrasion resistance by manufacturing the front nozzle tip by casting, and by using the material as a heat resistant alloy, and also front and rear lengths of the front nozzle tip and By clearly limiting the thickness, the goodness and ease of casting can be ensured.

Claims (6)

An inner cell having a first passage through which a mixture of fine fuel and air discharged into the furnace from the fuel distribution pipe in the center and a second air for discharging the secondary air introduced from the air conduit between the inner cell into the furnace An outer cell installed to be isolated from the outside of the inner cell to have a passage, at least one central baffle to partition the first passage inside the inner cell, and at least one outer baffle to partition the second passage At a nozzle tip of a configured fine fuel burner; The nozzle tip is produced by dividing the nozzle tip into the front nozzle tip and the rear nozzle tip, wherein the front nozzle tip is produced by casting, and the front and rear lengths are 1/3 of the total length of the nozzle tip. Nozzle tip of burner. The method of claim 1, The nozzle tip of the fine fuel burner, characterized in that further comprising a thickness of the front nozzle tip is 6 ~ 10mm. The method according to claim 1 or 2, The material of the front nozzle tip is a heat-resistant alloy, the composition and composition ratio of carbon (C) 1.20 ~ 0.70 weight (%), silicon (Si) 2.00 ~ 2.50 weight (%), manganese (Mn) 2.00 weight (%) , Phosphorus (P) 0.040 weight (%), sulfur (S) 0.040 weight (%), nickel (Ni) 11-37 weight (%), chromium (Cr) 15-28 weight (%), characterized in that The nozzle tip of the fine fuel burner. The method according to claim 1 or 2, The nozzle tip of the fine fuel burner, characterized in that the surface of the nozzle tip has an inlet toward the rear of the second channel, the cooling pipe having an outlet toward the front of the second channel. The method of claim 4, wherein The nozzle tip of the fine fuel burner, characterized in that the refractory is coated on the surface of the cooling pipe by a plurality of anchors and mesh nets fixed to the outer cell. The method according to claim 1 or 2, Protruding jaws and central baffles respectively formed on both side surfaces and upper and lower portions of the inner nozzle tip of the front nozzle tip are hard facing with a stellite material having a thickness of 3 to 6 mm.

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